Vertical GaN Power MOSFET with Integrated Fin-Shaped Diode for Reverse Conduction

Abstract

A vertical GaN power MOSFET featuring an integrated fin-shaped non-junction diode (FDMOS) is proposed to improve reverse conduction and switching characteristics. Its static and dynamic characteristics are studied and analyzed by Sentaurus TCAD simulation. Compared with the conventional MOSFET (Con. MOS) with a body diode as a freewheeling diode (FWD), the FDMOS uses the integrated fin-shaped diode to reverse conduction, and thus, a low reverse turn-on voltage VON of 0.66 V is achieved, with a decreasing of 77.9%. Moreover, the Qrr of the FDMOS is reduced to 1.36 μC from 1.64 μC of the Con. MOS, without the minority carrier injection. The gate charge (QGD) of the FDMOS is significantly reduced because the fin structure reduces the gate area and transforms some part of CGD to CGS, and thus, a low switching loss is realized. The QGD, the turn-on loss (Eon) and the turn-off loss (Eoff) of the FDMOS are decreased by 56.8%, 33.8% and 53.8%, respectively, compared with those of the Con. MOS. In addition, the FDMOS is beneficial to reduce the parasitic inductance and the total chip area compared with the conventional method of using an externally connected Schottky diode as an FWD.